The present invention is directed to a novel and improved method and means for engaging and removing a ply of limp material, typically a piece of fabric, from a stack of such plies, and transporting the ply in a desired manner. In the production of garments, for example, it is conventional practice to cut simultaneously an entire stack of garment sections from a stacked lay-up of fabric sections. The cut stack of fabric sections is then transferred to a subsequent production operation, in which the sections are removed one at a time for sewing, etc.
In a continuing effort to automate production operations of all kinds, substantial effort has been devoted to the development of systems capable of lifting off and separating the uppermost ply of fabric from a stack of pre-cut fabric sections and transporting the separated ply to a desired location for performance of a production operation. Prior proposals for this purpose have involved the use of means such as suction devices or pressure sensitive tapes, for example, for lifting off the top ply of a stack. Other arrangements heretofore proposed have involved the use of needle-like elements for engaging and lifting off the uppermost ply of a stack. A still further proposal for this purpose is represented by the Lutts et. al. U.S. Pat. No. 3,756,587.
Many of the above mentioned prior proposed arrangements are effective at a certain level, but each has disadvantages of one kind or another which limits its usefulness. For example, in an operation in which all conditions are fixed, with a single size and shape of ply and with the ply being at all times of the same material, it is frequently possible to adjust and adapt one or more of the various prior art devices for operation at a reasonable level of efficiency. However, in a more typical operation, the equipment may be called upon to handle parts of a variety of sizes and/or shapes and also to handle parts of different materials for which the prior art devices are not well suited. Even where a production operation involves only a single size and shape of part, serious problems may be experienced in dealing with a plurality of materials on different occasions. All of the prior art systems, insofar as the applicant is aware, have significant shortcomings in an environment requiring the handling of a variety of materials and/or shapes.
In accordance with one aspect of the present invention, an improved method and means is provided for effectively and reliably engaging, lifting and separating a ply of fabric or other limp material from a pre-cut stack thereof. To this end, the arrangement of the invention includes a novel and improved association of means for holding and restraining a portion of the top ply and means for frictionally gripping an adjacent area of the restrained ply and moving with it, first to form a wave in the ply and next in sequence to nip the wave. The new apparatus includes means for maintaining the gripping means and the restraining means in a predetermined geometrical association while, at the same time, enabling each to be brought independently into controlled and adjustably yieldable contact with the ply stack. In this respect, it will be understood that different ply materials may have widely different characteristics of stiffness, thickness, weight, roughness or smoothness, susceptibility to damage or marking, etc. Moreover, with fabric plies involving patterned weaves, a ply may have varying thickness and a stack of such plies may be wavy and uneven as a function of the cumulative effect of the individual ply variations. The apparatus of the invention uniquely accommodates such variable conditions and provides for reliable and effective operation under a wide variety of conditions.
In accordance with another aspect of the invention, novel and improved arrangements are provided for effectively limiting and controlling the pickup of a single ply from a stack thereof. In a typical production operation, a stack of cut plies will have been derived from a prior die cutting operation, in which a cutting die is driven through a lay-up of fabric elements to cut out an entire stack of shaped plies. Often such dies are not ideally sharp, causing the edge area of adjacent plies to fuse together (if of synthetic material) or to become entangled (if of natural fiber). As a result, in the picking up of a single ply, one or more adjacent plies often are dragged along by the edges, such that more than one ply are removed and/or the top of the stack is disarranged. In accordance with the present invention, the ply gripping and nipping means are located in spaced relation to the ply edges and function to displace one edge of the ply inwardly of the stack. If additional plies are attached to the displaced edge, they are rolled over and carried along with it for a short distance, after which they are temporarily engaged and effectively secured by a stack hold down element. Upon further displacement of the uppermost ply, it is separated along its displaced edge from the secured, underlying plies. Thereafter, and prior to the next ply removal operation, the stack hold down element is raised well above the stack, to permit the rolled over ply to return to its normal, flat condition on the stack.
As a further significant feature of the invention, a ply transport shutter means is provided for cooperative action with ply nipping and lifting means such that, when a single ply has been separated off of the stack and lifted at one edge, a plate-like transport shutter is inserted between the stack and the partially lifted ply, to complete the ply separation and thereafter to remove the ply from the area of the stack to another location. It will be understood, in this respect, that even after being nipped and separated from the stack at one edge, a ply may still be fused or entangled with lower plies of the stack along its other edges, such that simply attempting to lift the ply from the stack might well cause removal or displacement of one or more additional plies. Pursuant to the present invention, the plate-like transport shutter is actuated for movement generally in a plane parallel to the surface of the stack, and is inserted between the stack and lifted ply, while the stack hold down is in operation and while the lifted ply is still nipped, to progressively sever or disengage the lifted ply from the remainder of the stack. The transport shutter moves from the nipped edge of the ply toward its free edge, to keep the ply in tension while effecting progressive edge engagement. At the end of the disengagement stroke of the shutter, the freed ply rests on the upper surface of the shutter and can be transported away when the shutter is retracted. To advantage, while one ply is being transported by the shutter, another can be nipped and lifted, enabling optimum overall efficiencies to be realized.
In accordance with another feature of the invention, a method and means of simple construction yet high effectiveness is provided for reorienting a fabric ply, as necessary, after separation and transfer, to assure proper alignment of the ply with the sewing machine or other production apparatus. In this respect, it will be appreciated that the initial stack of plies may be somewhat irregular from its preliminary handling. Thus, the uppermost plies of the stack, as they are presented to the nipping elements, may be less than perfectly positioned in the first instance and may in any event be subject to a certain amount of displacement and disorientation in the course of nipping, lifting and transporting. In practice, ideal conditions are almost never experienced, and the separated ply is thus often in need of final positioning and orientation before processing. In the system of the invention, final positioning and orientation are achieved by means of a pair of sweep arms, which engage an edge of ply and are actuated through a lateral sweep movement along the ply edge, while the ply is lightly urged in the direction of such edge. This combined action quickly positions and rotationally orients the ply with respect to the reference axes of the system.
For a better understanding and appreciation of the above and other features and advantages of the invention, reference should be made to the following detailed description of a preferred embodiment and to the accompanying drawings. It should especially be understood that many of the features of the invention may be used to advantage individually as well as in association with some or all of the other features.